FYI ... I believe my newer BMW battery will become discharge with our lite use of the X5 and I believe we can ruin a battery sooner this way. My plan .... I have showing up tomorrow a cigarette lighter "voltmeter" etc. called A "Jebsen 4in1 car charger" for $11.99 via Amazon. I will monitor the batter voltage with this! I will then fully charge the battery using a 021-0123 I already have for my boat.
And then I watch the voltage at rest. I suspect the x5 voltage will drop over weeks and as needed I will charge the battery weekly or bi-weekly? To make this easier I may need to install a plug in my x5 grill to go to directly to the battery "jump spot". At any rate ... I will not see the battery harmed or have the car ... strand me or my wife. I won't even let the X5 confuse me with failing systems because they aren't working right because of a low battery ... go figure.
I am a engineer this isn't rocket science but it isn't it just it works either! Shame on BMW for making such a stupid flawed design here!